Forgot to add that my Water Hycinth are doing very poorly. When I got them the leaves were nice and green. Now they are yucky yellowish and they have not grown at all.

The thing I do not understand is that this is my new Stocktank and I can not figgure out why the levels would be so high.

Read my post on "growing hyacinths"

It sounds like you have an iron deficiency. If I'm right, you can add a small amount of a chelated iron supplement to your pond and your hyacinths will recover. Your hyacinths will remove the phosphate once they recover.

The phosphate might be in your water supply. Call your water supplier to check. If it is in the water, doing a partial water change isn't going to help.

I have liquid chelated iron in my garage but when I read the directions it said do not swallow and harmful if swallowed so I am afraid to add it. Of couse I am thinking I should only add afew drops.

I also have Iron Sulfate I could use but I use that on my blueberries so am wondering if it would cause the water to go more acidic.

Iron supplements usually contain a bunch of micro-nutrients like copper, manganese, zinc, and maybe boron if you are lucky. These are toxic in large enough doses, thus the warning. All of these nutrients are good for your pond in moderation, but they are toxic in excess. You find all of these things in human multivitamins as well, but you wouldn't want too much.

I use Fertilome Liquid Iron, which contains 3.25% iron, .05% copper, .15% manganese, and .16% zinc. This is a good product to use because it doesn't contain too much copper, which in my mind is the most risky of the micronutrients for ponds. I add a tablespoon or two to 3000 gallons of water. Adjust accordingly. Plants can use iron in concentrations as low as .1 PPM, so it doesn't take much.

I have added iron sulfate to my pond as well but I'm not sure it works. Iron has bioavailability issues. I don't remember all the details, but it matters if it is ferric or ferrous sulfate. Also, the chelation helps keep the iron in an available form for a longer time in the Fertilome product.

If iron is the problem, you will notice improvement in just a few days.

There are phosphate binders on the market that can bind out phosphates to help lower the levels. This one here is all natural and provides other benefits such as adding trace meinerals, buffering ph and minor flocculation.

Here is a link that might be useful: phosphate control for ponds

Hyacinths also depend on water temperature. They tend not to grow too vigorously below 65°F or so. Adding the iron, as mentioned above, will help green them up. But the form of the iron is crucial - ferric forms will immediately precipitate out and not be available for the plants; even the ferrous forms can be fairly readily oxidized to the ferric forms and then precipitate out. Which is why it's best to use the chelated form. You can further help your plants along by adding a small amount of "stump remover" - this is the way it's sold in many hardware stores, Home Depot, etc. - it really is nothing more than potassium nitrate. Or you may be lucky to find that you can buy a bag of small amount of potassium nitrate directly (check out the fertilizer section of your garden center). They tend not to sell this since there are "other uses" that some people use potassium nitrate for. You can add approximately 1 tablespoon per 1000 gallons once a week with no impact on your fish. In this fashion you're providing a modest amount of nitrogen and potash to stimulate growth of the plants without adding phosphorous. You didn't indicate the nitrate levels in your pond but you might want to measure them before you start adding the potassium nitrate just to be on the safe side. The 1 tablespoon per 1000 gallons won't jump it significantly and should be taken up by your plants very rapidly (usually I find it's gone within a few hours) specially on bright sunny days and if the water temperature is moderately warm. As has been mentioned elsewhere by Larryl you can also add just potash. However, I've found that the combination usually tends to kick them into high gear. Long about July I'm putting bucket loads of water hyacinths through the shredder and into the compost pile! Hope this helps.
---David

I did put afew drops of the chealated liquid iron in the pond last night. Maybe its my immagination but I really think the water hycinths look greener today.

cokeisit - Thanks for the link to the phosphate buffers. I will try that next if the hycinths do not start growing foir me.

Well, today I am absoletly sure the Water Hycinth are much greener and even look like they are growing. Hurray!!! Thank you for the tip about the chealated Iron. I put afew more drops in today.

Well, apartently I was not doing enough because the Water Hycinth would green up some and then just go back to sickly yellow. It is not growing. I found something called FloraPride in Petco when I went back there today for more meds. Its for plant growth and adds potassium and Iron.

Put some in the pond. Will see if this helps.

You might not have added enough of the micro nutrient mix. I'll figure it out for you. Let's call your 300 gallon pond 1000 liters. This is one of those times when metric is the only way to go. We will shoot for 1 ppm. One-millionth of 1000 liters is one milliliter, or 1 gram of iron. If your mix is 4% iron, you need to add 25 grams of the mix, which is about an ounce.

A few drops just wasn't enough.